全文获取类型
收费全文 | 8061篇 |
免费 | 916篇 |
国内免费 | 486篇 |
专业分类
化学 | 1006篇 |
晶体学 | 14篇 |
力学 | 1058篇 |
综合类 | 154篇 |
数学 | 4221篇 |
物理学 | 3010篇 |
出版年
2024年 | 9篇 |
2023年 | 97篇 |
2022年 | 146篇 |
2021年 | 170篇 |
2020年 | 219篇 |
2019年 | 188篇 |
2018年 | 195篇 |
2017年 | 324篇 |
2016年 | 326篇 |
2015年 | 222篇 |
2014年 | 481篇 |
2013年 | 583篇 |
2012年 | 508篇 |
2011年 | 456篇 |
2010年 | 356篇 |
2009年 | 458篇 |
2008年 | 484篇 |
2007年 | 512篇 |
2006年 | 473篇 |
2005年 | 398篇 |
2004年 | 322篇 |
2003年 | 358篇 |
2002年 | 307篇 |
2001年 | 291篇 |
2000年 | 245篇 |
1999年 | 218篇 |
1998年 | 188篇 |
1997年 | 167篇 |
1996年 | 136篇 |
1995年 | 117篇 |
1994年 | 81篇 |
1993年 | 68篇 |
1992年 | 54篇 |
1991年 | 40篇 |
1990年 | 33篇 |
1989年 | 25篇 |
1988年 | 26篇 |
1987年 | 30篇 |
1986年 | 18篇 |
1985年 | 28篇 |
1984年 | 18篇 |
1983年 | 8篇 |
1982年 | 12篇 |
1981年 | 7篇 |
1980年 | 11篇 |
1979年 | 18篇 |
1978年 | 5篇 |
1977年 | 5篇 |
1976年 | 6篇 |
1969年 | 2篇 |
排序方式: 共有9463条查询结果,搜索用时 15 毫秒
121.
Kerr介质中级联三能级原子与压缩相干态相互作用的光子统计演化 总被引:6,自引:0,他引:6
本文研究了存在Kerr介质的高Q腔中压缩相干态与级联三能级原子相互作用的光子统计演化规律,讨论了光场参数、Kerr介质及相干振幅对平均光子数的影响. 相似文献
122.
123.
124.
Ar—Kr溶液扩散系数的分子动力学模拟及其与温度的关系 总被引:2,自引:1,他引:2
用分子动力学模拟方法研究确定Ar-Kr溶液的自扩散系数D1、D2和互扩散系数D12以及它们随温度变化的规律。结果表明,分别用Green-Kubo法和Einstein法得到的扩散系数在数值上一致;该溶液的3种扩散系数均满足D=D0e^E/RT关系。 相似文献
125.
2-巯基乙醇自组装膜电极对多巴胺电催化氧化及其分析应用 总被引:12,自引:0,他引:12
在裸金电极上制备了 2 巯基乙醇自组装膜电极 (ME AuSAMs) ,研究了多巴胺 (DA)在ME AuSAMs上的电化学行为 ,发现该膜电极对DA的氧化具有良好的电催化作用 ,氧化过电位降低了 3 94mV ,测得DA的扩散系数D为 9.1 4 5× 1 0 - 7cm2 s,初步探讨了电催化机理。采用水平衰减全反射 傅里叶变换红外光谱 (ATR FTIR)技术对ME AuSAMs进行了表征 ;方波伏安法 (squarewavevoltammetry ,SWV)测定DA ,其氧化峰电流与DA浓度在 2 .0 0× 1 0 - 6 ~ 1 .0 0× 1 0 - 4 mol L范围内呈线性关系 ;相关系数为 0 .9998,检出限为 4 .0 0× 1 0 - 7mol L。该电极用于DA药物针剂的测定 ,结果满意 相似文献
126.
Summary The complete error potential is used for the study of the correlation of molecules. The correlation can be seen as a relaxation of the electrons and a relaxation of the nuclei. From the Fermi sea, the electronic relaxation gives rise to a partial excitation of each orbital which collectively generates a linear, a surface or a volume pressure; the resulting forces acting on the nuclei are defined in a general theory of the intramolecular forces. H3, H
3
+
, the diatoms and the hydrid of the first nine elements are taken as examples. 相似文献
127.
Bernards T.N.M. Huls B.G. van Bommel M.J. 《Journal of Sol-Gel Science and Technology》1997,10(2):193-202
This article describes the SmartKom Companion, one of three demonstrators developed within the SmartKom project whose goal
has been to provide an intuitive and intelligent interface for non-expert users to everyday computer-based applications in
different scenarios of use. Conceived for the SmartKom Mobile scenario, the Companion allows intuitive multimodal interaction
for drivers and pedestrians. The development of the SmartKom prototypes was constantly accompanied by Wizard-of-Oz experiments
as well as system evaluations at different stages of the project. Some usability evaluation results relative to the SmartKom
Companion will also be presented. 相似文献
128.
A novel 3D metal-organic coordination polymer Pb(1,4-napdc)(DMF) (1,4-napdc=naphthalene-1,4-dicarboxylate) was synthesized at room temperature using slow vapor diffusion method to grow single crystal that has been analyzed by X-ray diffraction. The crystal belongs to orthorhombic with space group P212121. The unit cell parameters are as fellows: a=0.701 3(2) nm, b=1.407 6(3) nm, c=1.521 5(4) nm, V=1.501 8(6) nm3 and Z=4. In the crystal structure of Pb(1,4-napdc)(DMF), the square grids constructed with paddle-wheel units of Pb(Ⅱ) and 1,4-napdc links stack over each other to generate infinite 3D network, which has square apertures (1.158×1.158 nm2) along the crystallographic a-axis. The thermal stability of compound was investigated by differential scanning calorimetry and thermogravimetric analysis. CCDC: 293617. 相似文献
129.
The ethanol effect on the Trichoderma reesei cellulases was studied to quantify and clarify this inhibition type. To determine inhibition parameters of crude cellulase
and purified exoglucanase Cel7A, integrated Michaelis-Menten equations were used assuming the presence of two inhibitors:
cellobiose as the reaction product and ethanol as a possible bioproduct of cellulose fermentation.
It was found that hydrolysis of cellulose by crude enzyme follows a model that considers noncompetitive inhibition by ethanol,
whereas Cel7A is very slightly competitively inhibited. Crude cellulase is much more inhibited (K
iul=K
icl=151.9 mM) than exoglucanase Cel7A (K
icl=1.6 × 1015 mM). Also, calculated inhibition constants showed that cellobiose inhibition is more potent than ethanol inhibition both for
the crude enzyme as well as exoglucanase Cel7A. 相似文献
130.
Two simple methods to calculate the area and volume called improved square gridmethod and cube cutting method are proposed in this paper. For any plane curve orspace surface satisfying certain conditions, by our method, the error of measurement isof the second infinitive order of measuring unit (the side length of the square grid or theside length of the little cube) when the unit is small enough. And when some properties ofthe curve or the surface can be found or its varying bounds can be evaluated, it is pointedout, in order to make the error smaller than any given value, how small the length of themeasuring unit should be. 相似文献